Propellant composition cured with aziridinyl compounds



United States Patent C 3,147,161 PROPELLANT CGMPUSHTION CURED WlTl-ll AZHRIDENYL (IOWQUNDS Joseph F. Abere, White Bear Lake, and Robert Dean Lowrey, North Oaks Village, Minn, assignors to Minnesota Mining and Manufacturing Company, t. Paul, Minn, a corporation of Minnesota No Drawing. Filed June 19, 1961, Ser. No. 117,787

22 Claims. (Cl. 143-49) This invention relates to pyrotechnic compositions and more particularly to solid, integral, non-detonating pyrotechnic masses. This application is a continuation-in-part of our prior copending application Serial Number 694,078, filed November 4, 1957.

It is an object of the present invention to provide solid, integral, non-detonating pyrotechnic masses which are stable and resistant to deterioration at ordinary temperatures and which may be used as solid composite jet propellant compositions and as solid composite rocket grains, as well as in the preparation of fireworks, railroad fusees, flares, etc. 'It is a particular object of the present invention to provide novel solid composite propellants which maintain desirable physical properties even after having been subjected to cycles of temperature extremes. Another object of the present invention is to provide rocket propellants which have a uniquely desirable combination of physical properties, processing characteristics and ballistic properties. Additional objects will be apparent to those skilled in the art from reading the specification which follows.

In accordance with the above and other objects of the invention, it has been found that when a substantially liquid carboxyl-terrninated prepolymer containing an average of 2 or more carboxyl groups per molecule is mixed with an inorganic oxidizer and is cured with a po1yfunctional aziridine ring-containing compound having the formula:

CH Q(N \CRR n where Q is an n-valent radical containing no active hydrogen atoms, n is at least 2, N is linked to an atom having a valence of from 4 to 5 and R and R are selected from the group consisting of hydrogen and an alkyl group containing not more than 8 carbon atoms, a solid, integral, non-detonating pyrotechnic mass is produced which has highly advantageous properties. Preferably one of R and R" on each imine ring in the polyfunctional aziridine ring-containing compound is hydrogen and the other is hydrogen or a lower alkyl group, i.e., one containing up to four carbon atoms, such as methyl, ethyl, propyl and n-butyl.

The jet motors prepared according to the invention are found to be particularly valuable. Jet motors designed to be used with solid propellants ordinarily comprise a combustion chamber having a nozzle in the wall thereof, a solid propellant within the chamber, and a means for igniting the propellant. The propellant in this type of motor is a solid combustible material which, when ignited, generates gas which escapes at high velocity through the nozzle, thereby producing a thrust. Those jet motors which are designed for use with propellants which contain all of the oxygen necessary for combustion of the fuel therein are often called rocket motors. Certain other jet motors, such as ram-jet motors, depend at least in part upon the atmosphere surrounding them for oxygen.

Proper operation of these motors requires that the burning rate of the propellant shall be at a steady preselected value, since irregularities in burning produce wide airma l Patented Sept. 1, 1964 changes in pressure which sometimes destroy the motor. Since the burning rate of the propellant is directly proportional to the area over which the burning takes place, it is desirable not only that the burning area be closely controllable, but also that it be essentially constant throughout the life of the motor. Rocket motors are often designed with very low safety factors with respect to operating pressures, and therefore uncontrolled increases in burning areas often cause rupture of the motors. The extreme temperature variations to which such motors are commonly exposed prior to use cause considerable expansion and contraction of the propellant. These dimensional changes cause cracks in the propellant grain itself as well as pulling away of the propellant grain from the areas at which it is adhered to the rocket motor, and these cracks provide extra burning surfaces which in turn bring about excessive and undesirable burning rates and excessive increases in pressure.

So far as is known, no solid propellant grain has heretofore been produced which maintains suflicient tensile strength and elongation at extremely low temperatures (e.g., 90 P.) so that it can be successfully fired with consistency after it has been stored at such low temperatures. The cracks caused by cycling to extremely low temperatures are often so invisible that they cannot be detected and it is only on firing that it is determined whether the propellant has successfully withstood the low temperature. Consequently, the discovery of a solid composite propellant system which will successfully and consistently fire after repeated cycles from high to low temperatures is of major importance in this field.

It has now been found that the compositions of the present invention do incorporate these heretofore unattainable properties. They have been found to maintain sufllcient tensile strength and elongation at extremely low temperatures as well as at ambient and elevated temperatures so that they can be consistently fired with success even after aging cycles which include temperatures down to and below 90 F. They can be fired successfully at low ambient temperature, without any special precautions or requirements. They are relatively insensitive to moisture and can be mixed and compounded in simple mixing equipment; and they may be cast in inexpensive molds. When thus cast, they may be cured at surprisingly low temperatures, and when so cured they are remarkably free from gas formation. The systems are characterized further by requiring no solvents, so that they can be prepared as mixtures containing percent solids-forming components.

Among the other pyrotechnic compositions according to the present invention are fireworks, including railroad fusees, signal flares, smoke producers, tourbillions, hummers, whizzers, stars, cones, fountains, etc. These fireworks comprise a casing having therein a pyrotechnic composition according to the present invention. The compositions of the invention, when cured, are not liable to be shaken loose from the finished articles or to be cracked internally by normal or even careless handling and regardless of storage conditions for reasons given hereinabove. The danger of cavitation during the filling and consequent danger of explosion of the finished firework upon ignition is materially lessened or obviated since solvents are not ordinarily utilized with the compositions and since they are normally pourable liquids when first compounded. The need for a strong closure of the fireworks case is less than in the usual types of pyrotechnic compositions.

Prepolymers which are suitable for use in the present invention include the following:

1. Branched polyesters prepared directly from alcohols and acids.-Such polyesters may be reaction products of a poly-functional alcohol, one or more diols and one or o in more dibasic acids. Some examples are the reaction products of:

Branched polyesters may also be prepared from a polyfunctional acid, one or more diols and one or more dibasic acids. Some examples of these polyesters are the reaction products of:

Trimesic acid, diethylene glycol and adipic acid;

Citric acid, polyethylene glycol and adipic acid;

Citric acid, di-1,4-(2-hydroxypropoxy)benzene, fumaric acid and sebacic acid;

Benzene tetracarboxylic acid, propylene glycol, 1,4-butylene glycol and adipic acid;

Benzene tetracarboxylic acid; polyethylene glycol, and

maleic acid; and

Benzene tetracarboxylic acid; 2,2-diethyl 1,3-propanediol,

and diglycolic acid.

A further method of preparing branched polyesters is by reacting a polyfuuctional acid with a hydroxy or an amino acid. Some examples of these polyesters are the reaction products of: I

Benzene tetracarboxylic acid and 12-hydroxy stearic acid;

Benzene tetracarboxylic acid and N-methyl B-alanine;

Polyacrylic acid and hydracrylic acid;

Polyacrylic acid and N-methyl-omega-aminoundecanoic acid;

Polymethacrylic acid and N-methyl-6-amino caproic acid.

II. Linear plyesters.Some examples of these polyesters are the reaction products of:

Diethylene glycol and adipic acid;

Propylene glycol, sebacic acid and isophthalic acid; 2,2-dimethyl-1,3-propanediol and succinic acid; Neopentyl glycol and thiadipropionic acid; and Diethylene glycol and isophthalic acid.

III. Carboxy-terminated reaction products of polyesters or polyethers with anhydrides or dior poly-functional acids.-Some examples are the reaction products of:

A linear, hydroxyl-terminated polydiethylene glycol adipate extended with pyromellitic dianhydride;

A linear, hydroxyl-terminated polyester of 1,4-butylene glycol and diglycolic acid extended with 1,4,5,8-naphthalenetetracarboxylic dianhydride;

A linear, hydroxyl-terminated polyester of polypropylene glycol and isophthalic acid extended with cyclohexanetetracarboxylic dianhydride;

Pyromellitic dianhydride and polybutylene glycol;

Pyromellitic dianhydride and 3,4-dithia-1,6-hexaue diol;

1,4,5,8-naphthalenetetracarboxylic dianhydride and polypropylene glycol; and

Cyclohexanetetracarboxylic dianhydride and poly 3-methyl-1,4-butylene glycol.

Anhydride-extended polyether glycols may also be prepared from polyether alcohols and cyclic acid anhydrides. Some examples are the reaction products of:

The reaction product of propylene oxide and ethylene diamine with glutaconic anhydride;

i The reaction product of pentaerythritol with ethylene and propylene oxide with maleic anhydride; and A glycerine, ethylene oxide, propylene oxide reaction product of the formula:

and succinic anhydride, wherein x is a number from 1 to about 20 and y is a number from 1 to about 100.

Other examples would be reaction products of polyalkylene glycols with various dibasic acids, e.g., the reaction products of polypropylene glycol 2025 (i.e., a hydroxy-terminated polypropylene oxide with an approximate molecular weight of 2025) with adipic acid and of polybutylene glycol 2000 (a hydroxy-terminated polybutylene oxide with an approximate molecular weight of 2000) with succinic acid. 7 7

IV. Vinyl addition p0lymers.Some examples are polybutadiene; the partially hydrolyzed copolymer of maleic anhydride and butyl acrylate; and copolymers of: acrylic acid and butadiene; butyl acrylate, 2-cyanoethyl acrylate and acrylic acid; methacrylic acid and butadiene; crotonic acid and butadiene; acrylic acid and methoxyethyl acrylate; and acrylic acid, acrylonitrile and butadiene.

The carboxyl group-containing prepolymers which are cured by the method of the invention are further characterized by being substantially liquid at about 25 to 50 C. when devoid of volatiles (i.e., have a maximum viscosity of the order of about 10,000 poises), and contain an average of two or more carboxyl groups per molecule. It is preferable that these carboxyl group-containing prepolymers have viscosities of less than 1,000 poises at 25 C., contain an average of from about 2.0 to about 15 carboxyl groups per prepolymer molecule, have an acid content ranging from about 0.1 to about 3 milliequivalents per gram, and have a number average molecular weight (fi of between about 700 and 10,000. Where a faster gel time and a more rigid cured article are desired, it is preferred to use a prepolymer containing an average of more than two carboxyl groups per molecule. While they may contain free hydroxyl groups, the presence of such hydroxyl groups in the prepolymers is in general detrimental for the purposes of the invention because they will act as chain terminators. Preferably, the prepolymers used are substantially free from unreacted hydroxyl groups.

As noted, the prepolymers of the present invention are ordinarily liquid, solids forming resins of which the maximum viscosity is of the order of 10,000 poises (less than 1,000 poises preferred). The advantages of such limitations on the prepolymer are:

(1) Little or no shrinkage upon final curing.

(2) The liquid form of these polymers is important in compounding and molding, i.e., simple mixing equipment may in most instances be used and simple open molds may be used in place of high pressure and/or high temperature molds.

(3) The liquid form of the prepolymers makes it more simple to disperse the curing agent into the polymer itself. Polyfunctional aziridine ring-containing compounds of the invention (sometimes called curing agents herein for convenience) are soluble in or can be dispersed in the prepolymers. It is also possible when desired to put solid curing agents into solution with volatile solvents such as chloroform and mix this solution with the prepolymer (although this is not generally necessary). The solvent may then be removed as by evaporation.

(4) No gases are given off during curing, whereby bubble-free resins are obtained.

The level of the acid concentration of the prepolymer is preferably held to from about 0.1 to about 3.0 milliequivalents per gram. A level of fewer than .1 milliequivalents per gram acid concentration results in such a slow rate of reaction with the curing agents that the system is practically inoperative to produce the desired result. On the other hand, if an acid concentration of 3.0 milliequivalents per gram is exceeded, control of the reaction may be lost, resulting in over-heating. In addition, the higher acid concentrations also reduce pot life or working time. Similarly, when a prepolymer containing more than about fifteen carboxyl groups per molecule is utilized, the pot life of the mixture of the prepolymer and the curing agent is ordinarily unduly shortened.

When referring herein to carboxy carboxyl groups or free carboxyl groups, it is intended to mean carboxylic acid reactive groups. It will be obvious that in the case of vinyl-type polymers, the carboxyl groups may not be terminal in exactly the same sense as in polyestertype polymers. However, it is considered that in the former case at least a number of the carboxyl groups present are located near chain ends.

Referring to the formula for the polyfunctional aziridine ring-containing curing agents, supra, Q may be an aliphatic, aromatic or alicyclic organic radical which does not contain an active hydrogen but which may contain atoms other than carbon, such as oxygen, sulfur, etc. This includes, for example, compounds in which Q is AOZRIHSOF, wherein R"" is a divalent organic linking group which contains no active hydrogen, preferably, a divalent aliphatic, aromatic or alicyclic radical (such as N,N'-bis-2-methylethylene-1,3-benzene disulfonamide; N,N'-bis-1,2-ethylene-1,3-butanedisulfonamide; N,N'-bis- 1,2-ethylene-1,4-butanedisulfonamide and N,N-bis-l,2- ethylene-1,3-propanedisulfonamide) and compounds in which Q is a trivalent organic radical (such as N,NN"- trisethylenetrimesamide, N,N',N-tris-1,2-propylene tri mesamide; N,N',N"-tris-1,2-butylene-trimesamide; N,N', N"-tris-2,2-dimethylethylenetrimesamide, etc. The N,N', N"-tris-alkylenetrimesamides and their preparation are described in the copending application of George H. Smith, U.S. Serial No. 832,152, filed August 7, 1959). Q may also be wherein Y is either oxygen or -NH, x is either 0 or 1, and R is a divalent organic linking group (preferably a divalent aliphatic, aromatic or alicyclic radical) which may contain atoms other than carbon, e.g., oxygen, sulfur, etc., but does not contain any active hydrogen atoms, i.e., hydrogen which is active to the Zerewitinoff test (inert to Grignard reagents).

In still another group of alkylenimine derivatives which are employed in this invention, Q may contain a I 1: =O or ]|?=S radical, such as those compounds in which Q is I R 11O wherein R is a monovalent or divalent organic linking group (preferably aliphatic, aromatic or alicyclic) which may contain atoms other than carbon, e.g., oxygen, sulfur, etc., but does not contain any active hydrogen atoms, i.e., hydrogen which is active to the Zerewitinoff test (inert to Grignard reagents).

The phosphorus-containing alkylenimine derivatives include for example, N,N-diethyl-N',N-diethylenethiophosphoramide; N,N'-diethylenebenzene thiophosphorodiamide; N-(3-oxapentamethylene)-N,N-diethylene phosphoric triamide; N,N'-diethylene benzene phosphondiamide; N,N'-diethylene ethane phosphondiamide; butyl N,N'-diethylenephosphorodiamidate; butyl-N,N' di 2- G methylethylenephosphorodiamidate; heXyl-N,N-diethylene phosphorodiamidate; N,N'-dioctyl-N,N-diethylenephosphoric triamide; N,N,N-tris(l,1-dimethy1ethylene)- phosphoric triamide; N,N"-dibutyl N,N" diethylene phosphoric triamide; parachlorophenyl-N,N"-di-Z-methylethylene phosphoric diamide; 3 (N ethylenecarboxamidophenyl)-N,N-diethylenephosphorodiamidate; etc.

The carboxyl containing curing agents which are particularly preferred have the formula:

wherein Y, x, R, R and R" are as previously defined. When at is 0, the compound is a bis-1,2 alkylenamide. When Y is oxygen and x is 1, the compound is a bis-1,2- alkylene carbamate. When Y is NH and x is 1, the compound is a bis-1,2-alkylene urea, such as 1,6-hexamethylene N,N'-diethylene urea and toluylene-N,N-diethylene urea.

Bis-1,2-alkylene carbamates and their preparation are described in US. Serial No. 850,541, filed November 3, 1959. Generally, their preparation involves the reaction of a 1,2-alkylenimine in a water phase with a solution of a chlorocarbonate of a difunctional alcohol in a water immiscible organic solvent, in the presence of an acid acceptor, at a temperature between about 5 C. and 30 C.

Illustrative of the bis-carbamates which are useful as curing agents in the present invention are:

N,N'-bis-1,2-ethylene (1,4-butanediol) carbamate;

N,N-bis-1,2-propylene (1,4-butanediol) carbamate;

N,N'-bis-1,2-butylene (1,4-butenediol) carbamate;

N,N'-bis-l,2-ethylene (diethylene glycol) carbamate;

N,N-bis-1,2-butylene (diethylene glycol) carbamate;

N,N'-bis-l,2-ethylene (triethylene glycol) carbamate;

N,N'-bis-l,2-propylene (triethylene glycol) carbamate;

N,N-bis-1,2-butylene (triethylene glycol) carbamate;

N,N-bis-l,2-ethylene (polyethylene glycol-200) carbamate;

N,N-bis-l,2-ethylene (polyethylene glycol-400) carbamate;

N,N'-bis-l,2-ethylene (polyethylene glycol-1000) carbamate;

N,N'-bis-1,2-propylene (polyethylene glycol-1000) carbamate;

N,N-bis-1,2ethylene (polyethylene glycol-4000) carbamate;

N,N'-bis-l,2-ethylene (polypropylene glycol-1025) carbamate;

N,N-bis-l,2-ethylene (polybutylene glycol-500) carbamate;

N,I I-bis-1,2-ethylene[ 1,1-isopropylidenebis (p-cyclohexanol) carbamate;

N,N-bis-1,2-ethylene[1,1'-isopropylidenebis (p-phenyleneoxy) di-Z-propanol] carb amate;

N,N'-bis-1,2-ethylene phenylenoxydiacetamide;

N,N'-bis-1,2-ethylene phenylenoxy carbamate;

N,N-bis-l,2-ethylene-4,4-bis phenyl carbamate;

N ,N'bis-l,2-ethylene l, l '-isopropylidene-bis-phenylene) carbamate;

N,N'-bis-ethylene-resorcinol carbamate;

N,N'-biethylene bisphenol-A-carbamate, etc.

The preferred aromatic carbamates are represented by the above formula wherein R is 1,3-phenylene, 1,4- phenylene, 1,1'-isopropylidene-bis-phenylene, or l,1'-isopropylidene bis (p-phenyleneoxy) di-Z-propanol. The preferred aliphatic carbamates are represented by the above formula wherein R is a branched or straight chain alkylene radical having from about 4 to about 40, preferably from about 4 to about 20, carbon atoms. The case referred to above, U.S. Serial No. 850,541, is an application of George H. Smith and is copending herewith.

Bis-1,2-alkylenamides and their preparation are described in the copending applications of George H. Smith, U.S. Serial No. 832,152 (filed August 7, 1959), now Patent No. 3,115,474, Serial No. 840,255 (filed September 16, 1959), now Patent No. 3,115,482 and Serial No. 850,330 (filed November 2, 1959), now Patent No. 3,115,490. Generally, their preparation involves the reaction of an alkylenimine in an aqueous phase with a solution of a dicarboxylic acid halide in a water immiscible organic solvent in the presence of an acid acceptor at a temperature between about C. and 30 C. Illustrative of the N,N-bis-l,2-alkylenamides in accordance with this invention are N,N-bis-1,2-ethylenadipamide; N,N-bis-ethylenpentadecyladipamide; N,N-bis-1,2-butylenadipamide; N,N-bis-1,2-etl1ylenepimelamide; N,N'-bis-ethylene thiodipropionamide; N,N-bis-ethyleneoxydipropionamide; N,N'-bis-1,2-ethylenisosebacamide; N,N-bis-1,2-butylenisosebacamide; N,N-bis-l,2-ethylensebacamide; N,N-bis-1,2-ethylensuberarnide; N,N'-bis-1,2-propylensuberamide; N,N-bis-1,2-butylensuberamide; N,N-bis-1,2-ethylenazelaamide; N,N-bis-1,2-propylenazelaamide; N,N-bis-l,2-butylenazelaamide; N,N-1,2-ethylendodecanoyldicarboxylic acid amide; N,N-bis-1,Z-ethylentetradecanoyldicarboxylic acid amide; N,N-bis-1,Z-propylentetradecanoyldicarboxylic acid amide; N,N'-bis-1,2-ethylenhexadecanoyldicarboxylic acid amide; N,N-bis-l,2-ethylenoctadecanoyldicarboxylic acid amide; N,N'-bis-1,2-propylenoctadecanoyldicarboxylic acid amide; N,N'-bis-1,2-propylendodecanoyldicarboxylic amide; N,N-bis-1,2-pentylensebacamide; N,N-bis-l,2-ethylene nonadecanediamide; N,N'-bis-1,Z-ethylene-1,4-naphthalenedicarboxamide; N,N'-bis-l,2-propylene-1,4-naphthalenedicarboxamide; N,N'-bis-1,2-ethylene-4,4-bisphenyl dicarboxamide; N,N'-bis-1,2-propylene-4,4-biphenyldicarboxamide; N,N-bis-l,2-ethylene hexahydroterephthalamide; para- (N- l ,2-ethylene carboxamidophenyl) -N-1,2-

ethylene acetamide; N,N-bis-l ,2-ethylenisophthalamide; N,N-bis-1,1-dimethylethlenisophthalamide; N,N-bis-l,2-butylenisophthalamide; N,N'-bis-1,2-octylenisophthalamide; N,N-bis-1,2-ethylcne hexahydroisothalamide; etc.

acid

The preferred aliphatic bis-1,2-alkylenamides are represented by the above formula wherein R is a branched or straight chain alkylene radical having from about 4 to about 40, preferably from about 4 to about 20, carbon atoms. The preferred aromatic bis-1,2-alkylenamides are represented by the above formula wherein R is 1,3- phenylene, 1,4-pl1enylene, 1,4-napthalene, or 4,4-bisphenyl.

In the preparation of the curedcompositions of the invention, the polycarboxyl group-containing prepolymers are employed in liquid form, and if necessary may be warmed slightly to liquefy them. To the selected liquid polycarboxyl prepolymer is then added first the oxidizer and any additives which may be required if particular types of fireworks are to be prepared then the curing agent which is to be employed. While an amount of the curing agent which is equivalent stoichiometrically to the number of carboxyl groups present may be employed, and some curing effect can be obtained with even smaller amounts, full cures are elfected when amounts greater than stoichiometric amount are employed, ranging upwards from 10 to 100 percent greater; in order to accomplish crosslinking and/or to compensate for any inerts in the curing agent, its absorption on oxidizer, etc. The cure is initiated as soon as the carboxyl group-containing prepolymer and the curing agent are mixed. The rate of cure is dependent to a degree upon the temperature, the viscosity of the mixture and the amount of the curing agent which is employed. Obviously, by maintaining the mixture at low temperatures, for example, about 0-10 C., the polymerization is retarded and increased pot life is obtained.

The practical maximum efficiency of burning in composite solid rocket propellants (in which all of the oxidizer necessary to firing is carried in the propellant) is achieved when the fuel (the organic portion) and the oxidizer are balanced so that the products of combustion of the carbon and hydrogen of the fuel are carbon monoxide and steam. In the composite rocket grains of the present invention, this maximum ordinarily occurs at fairly high oxidizer concentrations, i.e., from about 75 percent to about percent by weight of the total propellant. It has also been found that propellant compositions containing about percent or more of oxidizer are rather stiff and dry and difficult to process, although these may be formed by molding and extrusion techniques. In ram-jet motors, oxygen from the surrounding atmosphere can be utilized. Thus oxidizer concentrations as low as about 40 percent are often more efficient in these motors since more fuel can then be carried. The fireworks prepared according to the invention are widely varied in their compositions. Some are designed to carry all of the oxygen necessary to react with the fuel therein while others depend in part upon atmospheric oxygen. The fireworks thus may comprise anywhere from about 20 to 90 percent by weight of oxidizer. The operative range of oxidizer concentration for the purposes of the invention is from about 20 percent to about 90 percent of oxidizer based on the total weight of the pyrotechnic mass.

The type of oxidizing agent usable is not limited beyond the usual requirements of pyrotechnic masses of the type described. Useful oxidizers are finely divided solid ammonium, alkali metal or alkaline earth metal nitrate or an alkali metal or alkaline earth metal chlorate or an ammonium, alkali metal or alkaline earth metal perchlorate or chromate, etc., as well as certain organic oxidizers. Among the oxidizing agents which are useful are ammonium perchlorate, ammonium nitrate, potassium perchlorate, postassium chlorate, potassium nitrate, strontium nitrate, strontium perchlorate, barium nitrate, barium perchlorate, sodium nitrate, sodium perchlorate, sodium chlorate, copper nitrate, barium chlorate, ammonium dichromate, urea nitrate, hydrazine nitroforrnate, guanidine nitrate, triaminoguanidine perchlorate, etc.

The oxidizers are usually blended into the pyrotechnic compositions in finely divided form to assure intimate and uniform mixing. If highly consistent performance on firing is necessary, as in a rocket propellant, the particle size of the oxidizing agent must be controlled, since particle size variations affect the burning rate. Ammonium perchlorate is the preferred oxidizer in the present invention since it is non-hygroscopic, contains a large percentage of oxygen available for combustion, is stable both alone and in combination with the organic fuel, and is readily available commercially at a comparatively low price.

If desired, the properties of the pyrotechnic masses can be modified by incorporating in them any of the number of different types of additives which are well known to those skilled in the art. Among the additives which may be used in the solid composite rocket grains according to the invention are burning rate additives,

such as ammonium oxalate, to slow the burning, and silica, copper chromite and silver Wire (embedded in the propellant) to speed up burning; reinforcing agents such as carbonaceous fillers; inorganic fuels, such as finely divided aluminum or magnesium; plasticizers; catalysts; etc. The additives which may be used in the fireworks compositions of the invention include colored smoke producing materials such as oil green, oil orange, rhodamine B (a basic red dye); colored flame producers such as barium oxalate, strontium oxalate, strontium nitrate and barium chlorate; spark producers such as aluminum, magnesium or iron particles (provided that the magnesium and iron particles should be coated with a varnish, e.g., a stearate base shellac varnish to prevent reaction with other components of the firework composition); smoke producing materials such as hexachloroethane, naphthalene; etc.

The preparations of a number of carboxyl group-containing prepolymers suitable for use in the composition of the invention will now be given. These preparations are classified as above.

I. BRANCHED POLYESTERS Of the nine preparations of branched polyesters which follow, seven (A through E, H and J) illustrate the use of a polyfunctional alcohol, one or more diols and one or more dibasic acids, the eighth (F) illustrates the use of a polyfunctional acid, one or more diols and one or more dibasic acids and the ninth (G) illustrates the use of a polyfunctional acid and a hydroxy or an amino acid as starting materials for the desired products.

A. Bulk preparation of polyester of adipic acid, diethylene glycol and trimethyllpropane.-About 584 parts of adipic acid, 388 parts of diethylene glycol, 12.44'parts of trimethylolpropane and 2 parts of a triphenyl phosphite catalyst are charged to a stirred flask. The reaction is carried out at 160l80 C. in a nitrogen atmosphere. When approximately the theoretical amount of water of esterification has been driven olf (indicating that the reaction is essentially complete) the pressure is reduced gradually and the temperature is increased to 220 C. The reaction is terminated when the acid number of the melt reaches 27.9. The characteristics of the polyester are as follows:

Inherent viscosity in acetone 0.13 Number average degree of polymerization (i 50 Molecular weight (M 5000 Free carboxyl groups per molecule (average) 2.6 Acid concentration (milliequivalents per gram) 0.50

B. Bulk preparation of a polyester of adipic acid, diethylene glycol and glycerol.About 146 grams (1.0 mole) of adipic acid, 85.5 grams (0.80 mole) of diethylene glycol, and 9.2 grams (0.10 mole) of glycerol are charged to a stirred 250 milliliter flask. The reaction is carried out at 160-180 C. in a nitrogen atmosphere. The bulk of the water of esterification is removed (by distillation) within the first four hours and the remainder is then removed by lowering the pressure and raising the temperature of the reaction to 220 C. About two hundred grams of polymer are recovered. Its characteristics are as follows:

Inherent viscosity in acetone .08 Acid number (milligrams of potassium hydroxide per gram of sample) 58.0 Number average degree of polymerization (i 20 Molecular weight (M 2000 Free carboxyl groups per molecule (average) 3.0 Acid concentration (milliequivalents per gram) 1.04

C. Azeotropic preparation of a polyester 0; sebacic acid, neopentyl glycol and trimethylol pr0pane.About 202 parts of sebacic acid, 89.4 parts of neopentyl glycol and 3.7 parts of trimethylol propane are charged to a flask which is fitted with a Barrett trap, a thermometer which is immersed in the'liquid reaction mixture and a reflux condenser. A volume of benzene approximately equal to that of the reaction mixture is added and the liquid is heated to reflux. The refluxing is continued (the water of condensation being removed by the Barrett trap as it is formed) until the distillate becomes clear and the acid number of the polymer approaches the theoretical valve. The benzene is then removed by distillation. The characteristics of this polyester are as follows:

Number average degree of polymer'mation (i 23 Free carboxyl groups per molecule (average) 2.3 Acid concentration (milliequivalents per gram) .94 Acid number 53 D. Azeotropic preparation of a polyester of azelaic acid, oxypropylated bis-phenol A and trimethylol propane-About 188 grams (1 mole) of azelaic acid, 172 grams (0.5 mole) of 2,2-bis[4-(2hydroxypropoxy)phenyl] propane, 22.4 grams (0.116 mole) of trimethylolpropane, 1.0 gram of paratoluene sulfonic acid and 300 milliliters of benzene are charged to a 1 liter flask equipped with a Stark-Dean water-separator and a condenser. The mixture is heated at reflux until the theoretical amount of water has been removed. The characteristics of the polyester are as follows:

Number average degree of polymerization 10 Free carboxyl groups per molecule (average) 3.0 Acid concentration (milliequivalents per gram) 1.43 Acid number E. Bulk preparation of polyester of isosebacic acid, neopentyl glycol and trimethylolpropane.About 515 parts of isosebacic acid, 221 parts of neopentyl glycol and 13.5 parts of trimethylolpropane are charged to a stirred flask. The reaction is carried out at approximately 160180 C. in a nitrogen atmosphere. When approximately the theoretical amount of water of esterification has been driven oil (indicating that the reaction is essentially complete) the pressure is reduced gradually and the temperature is increased to 250 C. The reaction is terminated when the acid number of the melt reaches 60.6. The viscosity of the resulting polyester is found to be 3700 centipoises at F. when measured with a Brookfield viscometer.

F. The bulk preparation of the polyester of trimesic acid, diethylene glycol and adipic acid.-About 263 parts of adipic acid, 191 parts of diethylene glycol, 21 parts of trimesic acid and 650 parts of benzene are charged to a stirred flask and refluxed with agitation for about 6 hours. The water of condensation which forms during the reaction is removed in a Barrett trap. The benzene is removed at the end of the reaction leaving a mobile liquid polyester of which the acid number is 42 (acid concentration 0.75 milliequivalents per gram).

G. Balk preparation of the polyester of 'y-methyl-ecaprolactone and benzene tetracarboxylic acid-About 2500 parts of -methyl-s-caprolactone and 127 parts of benzene tetracarboxylic acid are heated together for 20 hours at 170 C. The resulting polymer is a viscous liquid with an acid number of 43 and an acid concentration of 0.77 milliequivalent per gram.

H. Balk polymerization of a polyester of adipic acid, diethylene glycol and trimethylol propane.About 579 parts of adipic acid, 350 parts of diethylene glycol, 20.8 parts of trimethylol propane and 2 parts of triphenyl phosphite are charged to a stirred flask. The reaction is carried out at 180 C. in a nitrogen atomsphere. When approximately the theoretical amount of water of esterification has been driven ofl (indicating that the reaction is essentially complete) the pressure is reduced gradually and the temperature is increased to 220 C. The reaction is terminated when the acid number of the 1 1 melt reaches 54. The characteristics of the polyester are as follows:

Number average degree of polymerization (i 25 Molecular weight (fi 2500 Free carboxyl groups per molecule (average) 2.5 Acid concentration (milliequivalents per gram) 1.0

I. Bulk polymerization of a polyester sebacic acid,

neopentyl glycol and trimethylol propane.--About 806 parts of sebacic acid, 350 parts of neopentyl glycol, 24 parts of trimethylol propane and 2 parts of triphenyl phosphite are charged to a stirred flask. The reaction is carried out at 160-180 C. in a nitrogen atmosphere. When approximately the theoretical amount of water of esterification has been driven off (indicating that the reaction is essentially complete) the pressure is reduced gradually and the temperature is increased to 220 C. The reaction is terminated when the acid number of the melt reaches 40. The characteristics of the polyester are as follows:

Number average degree of polymerization (i 30 Molecular weight (M 3000 Free carboxyl groups per molecule (average) 2.7 Acid concentration milliequivalents per gram 0.7

II. LINEAR POLYESTERS A. Bulk preparation of a linear polyester of adipic acid and diethylene glycol.About 500 parts of adipic acid and 295 parts of diethylene glycol are charged to a stirred flask. The reaction is carried out at 160200 C. in a nitrogen atomsphere. When approximately the theoretical amount of water of esterification has been driven off (indicating that the reaction is essentially complete) the pressure is reduced gradually and the temperature is increased to 220 C. The reaction is terminated when the acid number of the melt reaches 105. The characteristics of the polyester are as follows:

Number average degree of polymerization (I Molecular weight (IN I 1000 Free carboxyl groups per molecule (average) 2.0 Acid concentration (milliequivalents per gram) 2.0

III. CARBOXY-TERMINATED REACTION PROD- UCTS OF POLYESTERS OR POLYETHERS WITH ANHYDRIDES OR 131- OR POLY-FUNCTIONAL ACIDS A. Preparation of a polyether ester of a hydroxylterminated polyether of butylene oxide and pyromellitic dianhydride.About 100 parts of Dow Polyglycol B-1000 (a hydroxyl-terminated polyether of butylene oxide of an average molecular weight of 1000) is stirred and heated with 21.8 parts of pyromellitic dianhydride until the mixture reaches a viscosity of approximately 700 poises.

B. Preparation of a polyether-ester of a hydroxylterminated polyether and saccinic anrydride.-185 grams of a reaction product of glycerine, ethylene oxide, and propylene oxide of the general formula:

(Ill-I oH(oH OH2)xo(OH oI-Io),t

w CH2O(CHzCH2)x0(CH2CHO) H (3H H20(CHZCH2)sO(CH2CHO) H having an average molecular weight of about 1100 (Dow 15-100), 300 cc. of benzene and 28 grams of succinic anhydride are charged to a 1-liter stirred flask which is fitted with with a reflux condenser. The mixture is stirred and reacted for 8 hours at reflux. A small amount of water of condensation which forms during the reaction is removed in a Barrett trap. The benzene is removed by distillation and the resulting polyether is a 12 mobile, light yellow liquid. The acid number of the polyether is found to be 69.6.

C. Preparation of a polyether-ester of a hydroxylterminated polyether and saccinic anhydride-270 parts of a reaction product of ethylene oxide, propylene oxide and ethylene diamine of an average molecular weight of 2700 and represented by the formula:

are mixed with 40 parts of succinic anhydride and a catalytic amount of pyridine. The mixture is heated for four hours at 125 C. at which time the acid number has reached about 70. The polymer contains 4 carboxyl groups per molecule and the acid content is 1.25 miliequivalents per gram.

D. Preparation of a polyester of diethylene glycol, adipic acid and pyromellitic dianhya'ride.A glycol-terminated linear polyester is prepared by heating together 212 parts (2.0 moles) of diethylene glycol and 146 parts (1.0 mole) of adipic acid until the calculated amount of water is removed. The resulting prepolymer is condensed further by heating to 220 C. under a high vacuum and distillation of diethylene glycol until the inherent viscosity in acetone is about 0.06.

One hundred parts of the above hydroxyl-terminated polyester are heated with ten parts of pyromellitic dianhydride at 150 C. until the inherent viscosity in acetone amounts to about 0.10 and the acid number is 56 milligrams of KOI-I per gram.

IV. VINYL ADDITION POLYMERS A. Preparation of a copolymer of methoxyethyl acrylate and acrylic acid.-About 25 parts of methoxyethyl acrylate, 0.25 part of acrylic acid, 0.50 part of tertiary dodecyl mercaptan and 0.10 part of tertiary butyl peroxide are sealed in a heavy-walled glass ampoule in the absence of air. The sealed ampoule is held at C. (with agitation) for 20 hours. A liquid polymer is obtained which has an inherent viscosity in acetone of 0.11 and an acid number of 7.5.

B. Preparation of a copolymer of batadiene and acrylic acid-About 90 parts by weight of butadiene, 10 parts of acrylic acid, 180 parts of water, 5 parts of sodium lauryl sulfate, 5 parts of sodium sulfate, one part of potassium persulfate, and 6 parts of commercial grade tertiary dodecyl mercaptan are charged into a heavy walled pressure vessel. The vessel is sealed, placed in a water bath at 55 C. and agitated for 18-20 hours at which time the polymerization is 75'80% complete. The unreacted butadiene is bled off and the latex is coagulated by the addition of a 5% solution of barium chloride. The coagulated polymer is washed by agitating it with a large amount of water, and then blended with 1% parts of an antioxidant. The liquid polymer is dried by passing it over a hot drum drier. The product is a viscous liquid with an inherent viscosity of 0.19 and an acid number of 49.

C. Preparation of a copolymer of butadiene, acrylic acid and methacrylic acid.About 182 parts by weight of butadiene, 12 parts of acrylic acid, 6 parts of methacrylic acid, 344 parts of deionized water, 21.4 parts of sodium lauryl sulfate, .536 part of sodium bisulfite, 1.6 parts of potassium persulfate, 24 parts of commercial grade normal dodecyl mercaptain and 0.2 part of sulfuric acid are charged into a heavy walled pressure vessel. The vessel is sealed, and the charge is agitated very vigorously for a period of 24.8 hours, during which time a temperature of about F. is maintained. At the end of this reaction time, 0.66 part of hydroquinone dissolved in about 10 lbs. of water is added as a short stop and the unreacted butadiene is bled off. The latex is coagulated by the addition of parts of a 15% aqueous solution of sodium chloride and the coagulated polymer 13 is washed by agitating it with a large amount of Water and is then blended with 1 /2 parts of an antioxidant. Finally, the liquid polymer is dried under vacuum. A 60% conversion is obtained to a liquid polymer having a Brookfield viscosity at 25 C. of 288 poise and an acid concentration of 0.92 milliequivalent per gram.

In order more clearly to disclose the nature of the present invention, a number of specific products and compositions in accordance with the invention will now be described. It should be understood, however, that this is done solely by Way of illustration and is intended neither to delineate the scope of the invention nor limit the ambit of the appended claims. All parts are by weight in the examples unless otherwise specified and the solid constituents are utilized in finely divided form throughout.

Example 1 About 84.4 parts of finely divided ammonium perchlorate (which has been previously ground in a micropulverizer in order to break up agglomerates) are added to a Mogul mixer fitted with a sigma blade and containing 13 parts of the butadienezacrylic acid copolymer of preparation IVB above, and mixing is continued until a homogeneous mass is obtained. About 2.6 parts of N,N'-bis-1,2-butyleneisosebacamide are then blended into the mixture. The entire mixing operation is carried out at approximately 70 to 75 F. and under an absolute pressure of not more than 120 mm. of mercury.

The mixture is then poured into a cylindrical polytetrafiuoroethylene mold of which the internal dimensions are in depth and 1%" in diameter, and which contains a diameter central cylindrical core of the same material (this mold and core being designed for use in forming test composite rocket propellant castings, i.e., propellant grains). The mixture is then cured by placing the mold in an oven and maintaining it at 250 F. for 3 hours. At the endof that time, the mitxure is removed from the mold and is found to have cured to a solid, dark grey casting.

A 2 inch long segment of this cylinder is sawed from the casting and is mounted in a test motor which is a cylindrical combustion chamber having an internal diameter of 2 inches and a length of 5 inches. An exhaust nozzle (of which the throat diameter is 0.277 inch) is attached to one end of the motor which is mounted at its head end on a static firing stand. The motor is fitted with instruments for measuring the thrust of, and working pressure in the motor during firing. The grain (or propellant casting) is bonded by one of its planar surfaces to the head and of the motor, the other planar surface (which faces the nozzle) being coated so that it will not burn. Thus the burning surfaces for this firing will be the inner and outer cylindrical surfaces of the grain. Both the inhibition and the bonding of the grain are accomplished using a liquid polymer which has the same composition as the organic portion of the propellant grain itself (i.e., 5 parts of the butadienezacrylic acid copolymer and 1 part of N,N'-bis-1,2-butyleneisosebacamide).

For testing, the motor is cooled to dry ice temperature and fired by means of a nichrome igniter wire. The firing takes place smoothly, indicating that no cracks have occurred to vary the burning surface of the grain. Essentially flat pressure versus time and thrust versus time traces are obtained from this firing indicating a desirably uniform thrust throughout the burning cycle of approximately 0.7 second.

The ballistic parameters of this propellant grain are determined from this and several other firings of this composition (in which the length of the propellant grain cylinder, the cross-sectional area of the nozzle throat and the temperature of firing are varied). The following table summarizes the results of these runs (the above described run being run number one).

Grain Burning Tempera- Rate Average Specific Run No. ture at Kn fl (Inchcsl Pressure Impulse Firing second) (p.s.i.)

1! Ratio of burning surface to throat area. b Pounds of thrust per pound of propellant per second.

These ballistic parameters and the relationships between them are Well understood by those skilled in the art and are defined and derived in Rocket Propulsion Elements, by G. P. Sutton, John Wiley and Sons, Inc., New York, published 1949, pages 37 through 114, and this information is incorporated herein by reference.

The following physical test data are also obtained from the remaining portion of run 1 (test samples cured 3 hours at 250 F.).

At -94 F;

Tensile strength, p.s.i 678 Elongation, percent 31 At +70 F.:

Tensile strength, p.s.i 160 Elongation, percent 45 At +180 F.:

Tensile strength, p.s.i 25 Elongation, percent 25 These tensile and elongation tests are run on dumbbell test specimens (0.5 and 0.125 between bench marks) 0.5" thick at a jaw separation rate of 2"/minute. Test values correlate with those from ASTM D41251T.

A composition suitable for the production of colored smoke can be prepared by mixing 10 parts of sodium chlorate, 20 parts of starch (farina) and 10 parts of rhodamine B into 15 parts of the butadienezacrylic acid copolymer of preparation IVB in that order and then when a relatively uniform blend has been achieved, stirring in 3 parts of N,N-bis-1,Z-butyleneisosebacamide. The final blend is poured into suitable casings and heated for 3 hours at 250 F. to form tough, solid castings. Instead of the rhodamine B, another color forming ingredient may be used such as oil orange, or oil green.

Example 2 About 84.4 parts of finely divided ammonium perchlorate, 13 parts of the butadiene:acrylic acid copolymer of preparation IVB above and 2.6 parts of N,N-bis-1,2- butyleneisosebacamide are mixed as in Example 1. A motor of the type used in Example 1 is filled with the resulting viscous liquid propellant. This motor has previously been prepared to obtain good adhesion to the propellant by sand blasting the inside surfaces of the rocket motor, coating them with a thin film of the viscous liquid mixture of 5 parts of the butadienezacrylic acid copolymer used in the propellant grain and 1 part of N,N'-bis-1,2-butyleneisosebacamide and then curing this thin layer for 30 minutes at 200 F. A polytetrafluoroethylene mandrel is also inserted centrally in the motor so that a channel will be left in the propellant grain when it has been cured.

The propellant is cured by placing the motor in an oven at about 250 F. for about 3 hours. The motor is cooled to room temperature and the mandrel is removed from the solid rubbery propellant. The planar surface which will contact the nozzle when it is attached is coated with a liquid polymer consisting of 5 parts of the buta- 15 dienezacrylic acid copolymer of preparation IVB and 1 part of N,N-bis-1,2-butyleneisosebacamide. The nozzle is then attached and the assembly is heated to 250 F. for 2 hours to cure the inhibiting polymer. A nichrome igniter wire is placed in the channel, and the assembled motor is chilled at Dry Ice temperature for 24 hours, heated in a 180 F. oven for 18 hours, chilled again at Dry Ice temperature for 18 hours and finally warmed to room temperature and fired. A smooth firing is obtained thus indicating that no cracks had been opened by the extreme temperature cycle, either in the body of the propellant or between the propellant and the motor.

Example 3 About 74.8 parts of finely divided ammonium nitrate (which has been previously ground in a micro pulverizer in order to break up agglomerates), 20.8 parts of the polyester of ethylene glycol and adipic acid of preparation IA above, 1.8 parts of potassium dichromate (which is added as a burning catalyst) and 2.6 parts of N,N'-bis- 1,2-ethyleneisosebacamide are thoroughly mixed and a cylindrical propellant grain is cast by the procedure of Example 1.

An operative rocket is prepared by mounting a 3 /3" long segment of this grain in a test rocket motor of the type used in Example 1, bonding the grain to the rocket motor and coating the planar surface of the grain which faces toward the nozzle with a polymer which has the same composition as the organic portion of the propellant grain (i.e., 8 parts of the polyester to 1 part of the bis amide), coating the central channel of the propellant with a layer of the liquid propellant composition of Example 1 (in order to improve the ignition properties) and curing this layer by heating for 2 hours at 200 F.

A composition suitable for use in the manufacture of colored stars can be prepared by mixing 30 parts of potassium perchlorate, 5 parts of ammonium perchlorate, 2 parts of barium oxalate and 8 parts of wood charcoal into 16 parts of the polyester of preparation IA, in that order and then, when a relatively uniform blend has been achieved, stirring in 2 parts of N,N-bis-ethyleneisosebacamide. The final blend is poured into suitable casings and heated for three hours at 250 F. to form tough, rubbery castings.

Example 4 About 74 parts of finely ground ammonium perchlorate, 23.6 parts of the polyester of diethylene glycol and adipic acid of preparation IA above, and 2.4 parts of N,N-bis- 1,2-ethyleneisosebacamide are mixed and then poured into a polytetrafiuoroethylene mold to form a casting 4 inches long, 2 inches wide and 0.5 inch thick. The propellant is cured in an oven at 200 F. for 2 hours. This propellant has a tensile strength at 75 F. of 96 p.s.i. and an elongation of 58.3 percent. Its tensile strength and elongation at Dry Ice temperature are 652 p.s.i. and 42 percent, respectively, thus indicating that it can be stored and fired at temperatures of 80 F. and lower without difficulty.

Example 5 About 84.4 parts of finely divided ammonium perchlorate, 13 parts of the butadienezacrylic acid copolymer of preparation IVB above and 2.6 parts of N,N'-bis-1,2-ethyleneisosebacamide are mixed and the mixture is cast into a cylindrical propellant grain by the procedures of Example 1 and cured for a 2 hours in a 250 F. oven.

A 2 inch long segment of this cylinder is mounted in a test rocket motor, the bonding of the grain to the rocket motor and the inhibition of the non-burning surface being effected by a polymer which has the same composition as the organic (fuel) portion of the propellant grain. The motor is then mounted on the static firing stand, cooled to Dry Ice temperature and fired. The firing is successful, thus indicating that rockets propelled by this composition are capable of being stored and fired at Dry Ice temperature without adverse effects.

Example 6 About 75.3 parts of finely divided lithium perchlorate, 22.5 parts of the butadiene:acrylic acid copolymer of preparation IVB above and 2.2 parts of N,N'-bis-1,2- ethyleneisosebacamide are mixed. The resulting stiff, viscous mixture is cast into a cylindrical propellant grain by the procedures of Example 1 and cured for 2 hours in a 250 F. oven.

A 2 inch long segment of this cylinder is mounted in the previously described test rocket motor and the grain is bonded to the motor and the non-burning surface is inhibited with a polymer which has the same composition as that of the organic portion of the propellant grain. The motor is fired successfully, a heat of explosion of 1370 calories per gram of propellant being noted.

Example 7 About 81 parts of finely divided ammonium perchlorate, 17.3 parts of the neopentyl sebacate of preparation IC above and 1.7 parts of N,N'-bis-1,Z-ethyleneisosebacamide are mixed according to the procedure of Example 1.

The mixture is poured in a polyethylene mold to form a casting 4 inches long, 2 inches wide and 0.5 inch thick, which is then cured for 1 hour at 200 F. The tensile strength of this material is found to be 912 p.s.i. and its elongation 5 5 percent at approximately F. Its heat of explosion is found to be 1170 calories per gram.

A composition suitable for producing cones and fountains and colored lights can be prepared by mixing 25 parts of ammonium perchlorate, 10 parts of potassium nitrate and 2 parts of strontium nitrate into 17.3 parts of the neopentylsebacate of preparation IC, in that order and then, when a relatively uniform blend has been achieved, stirring in 1.7 parts of N,N'-bis-1,2-ethyleneisosebacamide. The final mix is then transferred to suitable casings and heated for one hour at 200 F. to form solid, rubbery fireworks.

Example 8 About 84.5 parts of finely divided ammonium perchlorate are added to a Mogul mixer fitted with a sigma blade and containing 14 parts of the butadienezacrylic acid copolymer of preparation IVB above, and mixing is contained until a homogeneous mass is obtained. 1.5 parts of N,N'-bis-1,2-ethyleneisophthalamide are then blended into the mixture. The entire mixing operation is carried out at approximately 70 to 75 F. and under an absolute pressure of not more than mm. of mercury. This raw propellant mixture has a pot life of 24 hours at room temperature which renders it extremely easy to use in the production of rocket propellant grains, particularly those of large size.

A composition according to the invention which is suitable for the production of cones, fountains and colored lights may be prepared by mixing 36 parts of ammonium perchlorate, 6 parts of finely divided aluminum and 2 parts of strontium oxalate into 16% parts of the butadiene: acrylic acid copolymer of preparation IVB, in that order, and then, when a relatively uniform blend has been achieved, stirring in 1% parts of N,N'-bis-ethyleneisophthalarnide. The mix is then transferred to suitable firework casings and heated until it has become a tough solid.

Example 9 A mixture of 40.5 grams of ammonium perchlorate, 40.45 grams of the butadienezacrylic acid copolymer of preparation IVB above, and 5.2 grams of N,N'-bis-l,2- propyleneisosebacamide is prepared according to the procedure of the previous example to form a raw propellant mixture which can be cast into a grain which, because of its relatively high fuel to oxidizer ratio, is particularly suited for use in a ram-jet motor.

Example 10 The butadienezacrylic acid copolymer of IVB above is mixed with ammonium perchlorate in the ratio of about 1 7 15.6 parts to 80 parts, and 4.4 parts of N,N-bis-1,2-ethyl-' enedodecanoyldicarboxylic acid amide are added subsequently. The mixture can be cured by heating for several hours at about 250 F. into a tough rubbery solid which is suitable for use as a solid rocket propellant.

A composition suitable for the production of tourbillions can be prepared by mixing 40 parts of potassium nitrate, 35 parts of potassium perchlorate and parts of oil green into 7.8 parts of the butadienezacrylic acid copolymer of preparation IVB, in that order and then, when a relatively uniform blend has been achieved, stirring in 2.2 parts .of N,N-bis-1,2-ethylenedodecanoyldicarboxylic acid amide. The mix is then transferred to suitable casings and heated for several hours at 250 F. until it has become solid. Closing of the tourbillion casings is not necessary from the functional point of view.

Example 11 The polyester of preparation IF above, is mixed with ammonium perchlorate in the ratio of about 16.6 parts to 80 parts, and 3.4 parts of N,N'-bis-1,2-ethyleneisosebacamide are added subsequently. The mixture can be cured by heating for several hours at about 250 F., yielding a tough rubbery solid which is suitable for use as a solid propellant grain.

A composition suitable for the production of a colored smoke can be prepared by mixing parts of sodium chlorate, 20 parts of starch (farina), 5.0 part of urea nitrate and 10 parts of oil orange into parts of the polyester of preparation IF, in that order and then, when a relatively uniform blend has been achieved, stirring in 3 parts of N,N-bis-1,2-ethyleneisosebacamide. The mix is then poured into casings and heated for several hours at 250 F. until it has become a tough, rubbery solid.

Example 12 The polyester of preparation IG, above, is mixed with ammonium perchlorate in the ratio of about 16.6 parts to 80 parts, and 3.4 parts of N,N-bis-1,2-ethyleneisosebacamide are added subsequently. The mixture can be cured by heating for several hours at 250 F. thus producing a tough rubbery solid which is suitable for use as a solid propellant grain.

A composition suitable for use in the manufacture of colored stars can be prepared by mixing 30 parts of potassium perchlorate, 5 parts of ammonium perchlorate, 2 parts of barium oxalate and 8 parts of wood charcoal into 15 parts of the polyester of preparation IG, in that order and then, when a relatively uniform blend has been achieved, stirring in 3 parts of N,N-bis-1,2-ethyleneisosebacamide. The final blend is then poured into firework casings and heated for several hours at 250 F. to form a tough solid.

Example 13 About 16.3 parts of the pyromellitic dianhydride-extended hydroxy terminated diethylene glycol adipate polyester of preparation HID above are mixed with about 80 parts of finely divided ammonium perchlorate. About 3.7 parts of N,N-bis-l,2-ethyleneisophthalamide dissolved in a small amount of chloroform are added and stirring is continued until the mixture is homogeneous. As the stirring and addition of curing agents are preferably done under reduced pressure, to avoid entrapment of air which would form bubbles, the chloroform is evaporated during stirring. The resulting mixture can be poured into molds and cured by heating for several hours at about 250 F., resulting in a tough solid which is suitable for use as a solid propellant grain.

Example 14 About 17.4 parts of the pyromellitic dianhydride-extended polyether glycol of preparation IIIA above are mixed with about 78 parts of finely divided ammonium perchlorate. About 4.6 parts of N,N'-bis-1,2-ethyleneisosebacamide (a 30 percent molar excess based on the free 18 carboxyl groups in the polyester) is added and stirring is continued until the mixture is homogeneous. It can then be poured into suitable molds and cured by heating for several hours at about 250 F., producing a solid system which is suitable for use as a solid propellant grain.

A composition suitable for the production of hummers can be prepared by mixing 20 parts of potassium nitrate into 7.9 parts of the pyromellitic dianhydride extended polyether glycol of preparation IIIA and, when a relative ly uniform blend has been achieved, stirring in 2.1 parts of N,N-bis-1,Z-ethyIene-isosebacamide. The mix is then transferred into suitable casings and heated for several hours until it has become a tough solid. In view of the nature of the cured material, closing of the hummer casings is not necessary from the functional point of view. The potassium nitrate may be replaced by 17.5 to 20 parts of potassium perchlorate.

Example 15 About 1.6 pounds of finely divided ammonium perchlorate are added with agitation to 0.24 pound of the polyether-ester of preparation IIIB above with agitation and 0.06 pound of N,N'-bis-1,2-ethyleneisosebacamide are added subsequently. After the mixture has been stirred until it is homogeneous it can be cast into suitable shapes and cured by heating for several hours at about 250 F., thus forming a solid which is suitable for use as a propellant grain.

A composition according to the present invention which is suitable for the production of whizzers can be prepared by mixing 20 parts of potassium nitrate into 8 parts of the polyetherester of preparation IIIB and, when a relatively uniform blend has'been achieved, stirring in 2.0 parts of N,N'-bis-1,2-ethyleneisosebacamide. The final mix is then poured into whizzer casings and heated for several hours at 250 F. until it has become solid. In view of the nature of the cured material, closing of the casings is not necessary from the functional point of view. The potassium nitrate can be replaced by 35 to 40 parts of potassium perchlorate.

Example 16 About parts of ammonium perchlorate, l6 par-ts of the polyether-ester of preparation IHC above and 4 parts of N,N-bis-l,2-ethyleneisosebacamide are mixed according to the procedure of the previous example, poured into suitable molds and cured by heating to about 250 F. over a period of several hours to form useful solid propellant grains.

Example 17 About 50 parts of finely divided ammonium perchlorate and 40.7 parts of the butadienezacrylic acid copolymer of preparation lVB above are mixed together for about 30 minutes. At the end of this mixing cycle 9.3 parts of N,N'-bis-1,2-ethylenesebacamide are added and mixing is resumed for an additional 30 minutes. The resulting mixture is quite fluid and is easily poured into a mold which is placed in a 200 F. oven for 16 hours. At the end of that time, the mixture is removed from the mold and is found to have cured to a solid, rubbery casting. The tensile strength of this material, which is suitable for use as solid rocket propellant grains, is found to be 28 pounds per square inch and its elongation is 5 6 percent.

Example 18 A mixture of 19.35 parts of the polyester of neopentylglycol, sebacic acid and trimethylolpropane of preparation I], 40.6 parts of ammonium perchlorate and 2.57 parts of toluylene-N,N-diethylene urea is prepared by adding the ammonium perchlorate to the polyester, stirring the two together carefully by hand until they have been well mixed and then stirring in the curing agent. Since this curing agent is a solid at room temperature, an infrared lamp is utilized to warm the mixture and facilitate the blending together of the constituents. The mixture is allowed to stand at room temperature fortwo days and is then subjected to 200 F. for three hours. At the end of that time it is cured to a tough, rubbery solid which is suitable for use as a solid composite rocket propellant.

Example 19 The polyester of I] is mixed with ammonium perchlorate in the ratio of about 19.35:44.4 parts, and 4.58 parts of N,N-bis-1,2-ethylene [1,1-isopropylidenebis (p-phenyleneoxy)di-Z-propanol] carbamate are added subsequently. Since this curing agent is a solid at room temperature, an infrared heat lamp is utilized to warm the mixture and facilitate the blending together of the constituents. The mixture is cured by allowing it to stand for two days at room temperature and then subjecting it to 200 F. for three hours. The resulting tough rubbery solid is suitable for use as a propellant grain in a rocket motor.

Example 20 About 39.6 parts of finely divided ammonium perchlorate are poured slowly into 19.35 parts of the polyester of I] with careful hand mixing. After these two have been stirred together until the resin has wet out the solid particles of oxidizer, 2.0 parts of butyl-N,N'- diethylenephosphorodiamidate are added and stirring is continued until a smooth blend has been obtained. The mixture is poured into a suitable mold, allowed to stand at room temperature for 48 hours and then heated at 200 F. for three hours to form a tough solid rocket propellant grain.

Example 21 The curing agent which is used in this example is 3-(N ethylenecarboxamidophenyl) N',N" diethylenephosphorodiamidate which has the structural formula:

052 /CH;; I N o ro- CON CH2 2 on,

It is prepared by adding a solution of 54.7 grams (0.2 mole) of m-chloroformylphenoxyphosphorous oxychloride in 300 milliliters of benzene to a stirred solution of 26.2 grams (0.61 mole) of ethylenimine and 82.8 grams (0.6 mole) of potassium carbonate in 150 milliliters of water at -12 C. over a period of about /2 hour. The stirring is continued for about one hour after the addition is complete. At the end of this time the benzene layer is separated, dried over crystalline sodium and calcium aluminum silicates (available commercially under the trade designation Molecular Sieve from the Linde Air Products Company), filtered and evaporated. The residue is an 86 percent yield (50.5 grams) of crude 3-(N ethylenecarboxamidophenyl) N',N" diethylenephosphorodiamidate which has a melting point of 7174 C., an aziridine ring content of 40.5 percent and a chlorine content of 0.4 percent, compared to calculated values of 43.0 percent and 0.0 percent, respectively.

Finely divided ammonium perchlorate is mixed into the neopentyl glycol sebacate polyester in the ratio of about 39.5 parts to 19.35 parts, and 1.89 parts of 3-(N ethylenecarboxamidophenyl) N',N diethylenephosphorodiamidate curing agent are added subsequently. The preparation of this blend is rather difiicult and the resulting mixture is itself rather stiff. It is allowed to stand for two days at room temperature and is then heated for three hours at 200 F. to form a tough, rubbery solid material which is suitable for use as a rocket propellant grain.

Example 22 The neopentylglycol sebacate of preparation I] is mixed with ammonium perchlorate in the ratio of about 19.35 parts to 40.4 parts, and 2.43 parts of viscous liquid 20 N,N',N"-tris-1,2-butylenctrimesamide curing agent are added subsequently. The constituents mix rather easily, the curing agent being a viscous liquid. The mixture is allowed to stand for two days at room temperature and is then heated for three hours at 200 F. to form a tough, rubbery casting suitable for use as a composite rocket propellant grain.

Example 23 The carboxyl-terminated prepolymer which is utilized in this example is a polybutadiene having the structural formula:

The average molecular weight of this prepolymer is approximately 60007000 (n equals about -130), it has an acid number in the range of about 16-17, contains an average of about 2 carboxyl groups per molecule and is available under the trade designation Butarez CTL from the Phillips Petroleum Co. of Bartlesville, Oklahoma. In addition to the 1,4 addition shown in the structural formula above, there appears to be a small amount of 1,2 addition (resulting in an occasional pendant vinyl group) and a small amount of acrylonitrile in the chain of this prepolymer.

About 37.3 parts of ammonium perchlorate in finely divided form are mixed into 18.9 parts of the carboxylterminated polybutadiene prepolymer and, after these constituents have been mixed thoroughly, 1.2 parts of toluylene-N,N-diethylene urea are added. In view of the fact that the curing agent is a solid at room temperature, an infrared heat lamp is utilized to Warm the mixture and thereby facilitate the blending together of the constituents. The mixture is allowed to stand for two days at room temperature and is then cured for 3 hours at 200 F. to form a solid, tough casting suitable for use as a solid composite propellant grain.

Example 24 A mixture of 39.1 parts of finely divided ammonium perchlorate and 18.9 parts of the carboxyl-terminated polybutadiene described in Example 23 is prepared by mixing the two constituents together by hand and 2.14 parts of N,N-bis-1,2-ethylene [1,1-is0propylidene-bis (p-phenyleneoxy)di-2-propanol] carbamate are added subsequently and mixing is continued until a uniform blend is attained. Since the curing agent is a solid at room temperature, an infrared heat lamp is utilized to warm the mixture and facilitate the blending together of the constituents. The mixture is allowed to stand for 48 hours at room temperature and then is cured for 3 hours at 200 F. to form a tough, coherent mass suitable for use as a composite rocket propellant grain.

Example 25 About 37.2 parts of finely divided ammonium perchlorate are added to 18.9 parts of the carboxyl-terminated polybutadiene described in Example 23 and the two are stirred together by hand until a relatively even mixture is obtained. 1.13 parts of N,N-bis-ethyleneisosebacamide, a water white liquid, are then added and the entire mixture is stirred by hand until thoroughly blended. The mixture cures in two days at room temperature to a rubbery, tough mass which is suitable for use as a solid composite rocket propellant grain.

Example 26 The carboxyl-terminated polybutadiene described in Example 23 is mixed with ammonium perchlorate in a ratio of about 18.9 parts to about 37.2 parts, 1.13 parts of N,N'-bis-1,2-propylenisophthalamide are added subsequently and the mixture is stirred by hand until thoroughly blended. It is allowed to stand for two days at room temperature and is then heated for 21 hours at 200 F. to form a tough, coherent mass which is suitable for use as a solid propellant grain.

21 Example 27 A mixture of 37.9 parts of ammonium perchlorate, 18.9 parts of the carboxyl-terminated polybutadiene described in Example 23 and 1.52 parts of N,N-bis-1,2-butylenisosebacamide is prepared according to the procedure of the previous example. The mixture is allowed to stand for 48 hours at room temperature and is then heated for 3 hours at 200 F. to form a solid casting suitable for use as a composite rocket propellant grain.

Example 28 About 36.8 parts of ammonium perchlorate are mixed with 18.9 parts of the carboxyl-terminated polybutadiene described in Example 23 and about .88 part of solid 3-(N- ethyleneearboxamidophenyl) N'N diethylenephosphorodiamidate are added subsequently. Some difiiculty is encountered in achieving good mixing in view of the fact that the curing agent is a solid. The resulting mix is allowed to stand for two days at room temperature and is then heated for 21 hours at 200 F. to form a tough, solid, coherent mass which is suitable for use as a solid composite rocket propellant grain composition.

Example 29 A mixture of 18.9 parts of the carboxyl-terminated polybutadiene described in Example 23, 37.2 parts of am monium perchlorate and 1.13 parts of N'N,N"-tris-1,2- butylene-trimesamide is prepared by adding the ammonium perchlorate to the polybutadiene, stirring the two constituents together carefully by hand until they have been well mixed and then stirring in the curing agent. This curing agent is a viscous liquid at room temperature and no difliculty is encountered in forming a smooth blend. The mixture is allowed to stand for two days at room temperature, during which time no curing appears to take place, and then is heated for three hours at 200 F. to form a tough, solid, rubbery mass which is suitable for use as a composite rocket propellant grain.

Example 30 A mixture of 44.6 parts of ammonium perchlorate, 20.6 par-ts of the branched diethyleneglycol adipate polyester of preparation IH have and 3.43 parts of toluylene-N,N- diethylene urea is prepared by adding the ammonium perchlorate to the polyester while mixing by hand and subsequently adding the curing agent. The curing agent is a solid at room temperature and an infrared lamp is therefore utilized to warm the mixture and facilitate the blending together of the constituents. This blend cures in two days at room temperature to a tough, coherent mass suitable for use as a solid composite rocket propellant grain.

A composition suitable for the production of colored smoke can be prepared by mixing parts of sodium chlorate, 20 parts of starch (farina) and 0.5 part of urea nitrate into 15.5 parts of the branched diethyleneglycol adipate polyester of preparation IH. When a relatively uniform blend has been achieved, 2.6 parts of toluylene-N,N-diethylene urea and 10 parts of rhodamine B are stirred into the mixture. The final mixture is then transferred into suitable firework casings and allowed to stand for two days at room temperature to form tough, solid castings.

Example 31 A mixture of 49.6 parts of finely divided ammonium perchlorate, 20.6 parts of the same branched diethylene- Example 32 The polyester of preparation 11-1 is mixed with ammonium perchlorate in the ratio of about 20.6 to about 43.2 parts, and 2.66 parts of butyl-N,N'-dietl1ylenephosphorodiamidate are added subsequently. The mixture is allowed to stand for 48 hours at room temperature and is then heated for 3 hours at 200 F. to form a tough, coherent, rubbery mass which is suitable for use as a solid composite rocket propellant grain.

A composition suitable for use in the manufacture of colored stars is prepared by mixing 30 parts of potassium perchlorate, 5 parts of ammonium perchlorate, 2 parts of barium oxalate and 8 parts of wood charcoal into 16 parts of the branched diethyleneglycol adipate polyester of perparation IH and subsequently stirring in 2 parts of butyl-N,N-diethylenephosphorodiamidate. This mix is then transferred to suitable casings and heated for four hours at 200 F. to form tough, solid, rubbery castings.

Example 33 A mixture of 16.32 parts of the liquid butadiene:acrylic acid:methacrylic acid copolymer of preparation IVC above, 35.1 parts of finely divided ammonium perchlorate and 2.57 parts of toluylene-N,N-diethylene urea is prepared by adding the ammonium perchlorate to the liquid copolymer, stirring them together carefully by hand until they have been well mixed and then stirring in the curing agent. As this curing agent is a solid at room temperature, an infrared heat lamp is utilized to warm the mixture and thereby facilitate the blending together of the con stituents. The mixture is allowed to remain for two days at room temperature and then is heated for three hours at 200 F. to form a coherent, tough, solid mass which is suitable for use as a solid composite rocket propellant grain.

Example 34 A mixture of 38.8 parts of ammonium perchlorate, 16.32 parts of the liquid copolymer of preparation IVC and 4.58 parts of N,N-bis-l,2-ethylene[1,1'-isopropylidenebis(p-phenyleneoxy)di-2-propanol1carbamate is prepared according to to the procedure of the previous example, this curing agent also being a solid at room tem' perature. The mixture is allowed to stand for two days at room temperature and then is cured for three hours at 200 F. to form a tough, rubbery, solid mass which is suitable for use as a composite propellant grain.

A composition suitable for producing cones, fountains and colored lights is prepared by mixing 25 parts of ammonium perchlorate, 10 parts of potassium nitrate and 2 parts of strontium nitrate into 14 parts of the liquid copolymer of preparation IVC and subsequently adding 4 parts N,N'-bis-1,2-ethylene[l,l'-isopropylidenebis(pphenyleneoxy)di-2-propanol]carbamate. The mix is then transferred into suitable casings and heated for 4 hours at 200 F. to form tough, solid castings.

Example 35 A mixture of 16.32 parts of the copolymer of preparation IVC, 34.82 parts of finely divided ammonium perchlorate and 2.43 parts of N,N,N"-tris-1,2-butylene-trimesamide is prepared by adding the ammonium perchlorate to the copolymer, stirring the two together carefully by hand until they have been well mixed and then stirring in the curing agent. A smooth blend is attained easily since the curing agent is a viscous liquid. The mixture is allowed to stand for one day at room temperature and is then heated for three hours at 200 F. to form a tough, rubbery, solid coherent mass which is suitable for use as a composite rocket propellant grain.

A composition according to the invention which is suitable for the production of red stars can be prepared by mixing 34.8 parts of the liquid copolymer of preparation IVC with 10 parts of strontium nitrate and 10 parts of aluminum powder, 40 parts of ammonium perchlorate 23 being added subsequently. Finally, after a relatively uniform blend has been achieved, 5.2 parts of N,N',N- tris-1,2-butylene-trimesamide are stirred in. The mix is then transferred to suitable firework casings and heated for 4 hours at 200 F. to form tough, solid castings.

Example 36 A mixture of 16.02 parts of the linear diethyleneglycol adipate polyester of preparation VA above, 38.8 parts of finely divided ammonium perchlorate and 4.86 parts of N,N'-bis-ethylenisosebacamide is prepared according to the procedure of the previous example, a smooth blend being easily achieved. The mixture is allowed to stand for two days at room temperature during which time it cures to a tough, rubbery, solid composition which is suitable for use as a rocket propellant grain.

Example 37 A mixture of 16.02 parts of the linear diethyleneglycol adipate polyester of preparation VA above, 36.8 parts of ammonium perchlorate and 3.78 parts of 3-(N-ethylenecarboxarnidophenyl) N,N diethylenephosphorodiamidate is prepared by adding the ammonium perchlorate to the polyester, stirring them together by hand until they have been well mixed and then stirring the curing agent in. Since this curing agent is a solid at room temperature, an infrared heat lamp is utilized to warm the mixture and facilitate the blending together of the constituents. The mixture is allowed to stand for two days at room temperature and is then heated for three hours at 200 F. to form a solid casting suitable for use as a composite rocket propellant grain.

Example 38 A mixture of 38.8 parts of ammonium perchlorate, 16.02 parts of the linear diethyleneglycol adipate polyester of preparation VA and 4.86 parts of N,N,N"-tris- 1,2-butylene-trimesamide is prepared according to the procedure of the previous example. The mixture is allowed to stand for two days at room temperature and is then heated for 48 hours at 200 F. to form a tough, rubbery solid which is suitable for use as a composite rocket propellant grain.

The terms and expressions which have been employed are used as terms of description and not of limitation, and it is not intended, in the use of such terms and expressions, to exclude any equivalents of the feature shown and described or portions thereof, but it is recognized that various modifications are possible within the scope of the invention claimed.

What is claimed is:

1. A solid composite propellant for jet propulsion motors consisting essentially of a mixture of from about to about 60 percent of a polymer comprising a carboxylterminated prepolymer consisting of a reaction product of adipic acid, diethylene glycol and trimethylol propane containing an average of more than 2 carboxyl groups per molecule, cured by heating at a temperature above about 10 C. with an amount ranging from the stoichiometric equivalent amount up to a 100 percent excess 01" the stoichiometric amount of N,N'-bis-1,Z-ethyleneisosebacamide; and from about 90 to about 40 percent of finely divided ammonium nitrate.

2. A solid composite propellant for jet propulsion motors consisting essentially of a mixture of from about 10 to about 60 percent of a polymer comprising a butadiene: acrylic acid prepolymer containing an average of more than 2 carboxyl groups per molecule cured by heating at a temperature above about 10 C. with an amount ranging from the stoichiometric equivalent amount up to 100 percent excess of the stoichiometric amount of N,N-bis-1,2- butyleneisosebacamide; and from about 90 to about 40 percent of a finely divided inorganic oxidizing agent.

3. A solid composite propellant for jet propulsion motors consisting essentially of a mixture of from about 10 to about 60 percent of a polymer comprising a butadiene: acrylic acid prepolymer containing an average of more than 2 carboxyl groups per molecule cured by heating at a temperature above about 10 C. with an amount ranging from the stoichiometric equivalent amount up to a 100 percent excess of the stoichiometric amount of N,N-bisl,2-ethyleneisosebacamide, and from about 90 to about 40 percent of finely divided lithium perchlorate.

4. A solid integral, non-detonating pyrotechnic mass comprising (1) about 10 to percent of the cured product of (a) a substantially liquid carboxyl-terminated prepolymer which contains an average of not less than about 2 carboxyl groups per molecule, has an acid content in the range of about 0.1 to 3 milliequivalents per gram and which is selected from the class consisting of polyesters and vinyl addition polymers with (b) an at least stoichiometric amount of a polyfunctional aziridine ring-containing compound of the formula:

wherein R is an n-valent hydrocarbon radical which contains no active hydrogen, Y is selected from the class consisting of O- and NH-, R and R" are selected from the class consisting of hydrogen and alkyl radicals containing from 1 to 8 carbon atoms, 11 is 2 to 3 and x is 0 to 1, and

(2) about to 20 percent of a finely divided solid oxidizing agent.

5. A pyrotechnic mass according to claim 4 adapted for use as a composite propellant for jet propulsion m0- tors comprising (1) about 10 to 60 percent of the said cured product and (2) about 90 to 40 percent of the said oxidizing agent.

6. A pyrotechnic mass according to claim 4 adapted for use as a composite firework.

7. A pyrotechnic mass according to claim 4 wherein n is 2 in the aziridine ring-containing compound.

8. A pyrotechnic mass according to claim 7 wherein x is 1 and Y is -O.

9. A pyrotechnic mass according to claim 8 wherein the aziridine ring-containing compound is N,N-bis-1,2- ethylene[l,1' isopropylidene bis(p phenyleneoxy)di- 2-prop anol] carbamate.

10. A pyrotechnic mass according to claim 7 in which x is 1 and Y is NH in the aziridine ring-containing compound.

11. A pyrotechnic mass according to claim 10 wherein the aziridine ring-containing compound is toluylene-N,N- diethylene urea.

12. A pyrotechnic mass according to claim 7 wherein x is 0 in the aziridine ring-containing compound.

13. A pyrotechnic mass according to claim 12 wherein R is an aliphatic radical containing from about 4 to about 40 carbon atoms.

14. A pyrotechnic mass according to claim 12 wherein R is an aromatic radical.

15. A pyrotechnic mass according to claim 4 wherein the aziridine ring-containing compound is an N,N,N"- tris-1,2-alkylentrimesamide.

16. A pyrotechnic mass according to claim 4 wherein the prepolymer is a polyester.

17. A pyrotechnic mass according to claim 4 wherein the prepolymer is a vinyl-addition polymer.

18. A pyrotechnic mass according to claim 7 wherein the prepolymer is a carboxyl-terminated acrylic acid-vinyl addition copolymer.

25 26 19. A pyrotechnic mass according to claim 17 wherein tors according to claim 12 wherein the prepolymer is an the prepolymer is a carboxyl-terminated polybutadiene. acrylic acid vlnyl'additloll p y 22. A propellant according to claim 21 wherein the 20. A solid composite propellant for jet propulsion moprepolymer 1s a butad1ene-acryl1c acid copolymer.

tors according to claim 12 wherein the prepolymer is a polyester of a polyfunctional organic acid with a poly- 5 References Cited in the file Of this Patent functivnal alcohol- UNITED STATES PATENTS 21. A solid composite propellant for jet propulsion mo- 3,028,271 Dixon et a1 Apr. 3 1962 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3, 1417 161 September I 1964 Joseph F, Abere et alq It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patentshould read as corrected below. 7

Column 10 line 8, for "valve" read value line l9 for "(2hydroxypr0poxy)" read (2-hydroxypropoxy) column 17 line 28, for "5,0" read O05 column 21 line 43, for "have" read above Signed and sealed this 9th day of February 1965:,

(SEAL) Attest:

ERNEST W. SWIDER EDWARD J. BRENNER Aim/sting Officer Commissioner of Patents UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent N00 5 1417 161 September 1 1964 Joseph F, Abere et alo It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 10 line 8 for "valve" read value line 19 for "(2hydroxypr0poxy)" read (2-hydroxypropoxy) column 17 line 28, for "5.0" read CD5 column 21 line 43 for "have" read above Signed and sealed this 9th day of February 1965',

(SEAL) Attest:

EDWARD J. BRENNER Commissioner of Patents ERNEST W. SWIDER Attesting Officer 

1. A SOLID COMPOSITE PROPELLANT FOR JET PROPULSION MOTORS CONSISTING ESSENTIALLY OF A MIXTURE OF FROM ABOUT 10 TO ABOUT 60 PERCENT OF A POLYMER COMPRISING A CARBOXYLTERMINATED PREPOLYMER CONSISTING OF A REACTION PRODUCT OF ADIPIC ACID, DIETHYLENE GLYCOL AND TRIMETHYLOL PROPANE CONTAINING AN AVERAGE OF MORE THAN 2 CARBOXYL GROUPS PER MOLECULE, CURED BY HEATING AT A TEMPERATURE ABOVE ABOUT 10*C. WITH AN AMOUNT RANGING FROM THE STOICHIOMETRIC EQUIVALENT AMOUNT UP TO A 100 PERCENT EXCESS OF THE STOICHIOMETRIC AMOUNT OF N,N''-BIS-1,2-EHTYLENEISOSEBACAMIDE; AND FROM ABOUT 90 TO ABOUT 40 PERCENT OF FINELY DIVIDED AMMONIUM NITRATE. 